The Tread Life of Tires Mounted on Light Duty Trucks

question 56

Multiple Choice

The tread life of tires mounted on light duty trucks follows the normal probability distribution with a mean of 60,000 miles and a standard deviation of 4,000 miles. Suppose you bought a set of four tires, what is the likelihood the mean tire life of these four tires is more than 66,000 miles?

• A) 0.0013
• B) 0.9987
• C) 0.4987
• D) 0.9544

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Definitions:

Varves

Thin, alternating light-colored and dark layers of sediment that form in lakes because of seasonal variations of deposition and biologic activity.

Ice Cores

Cylinder-shaped samples from ice sheets or glaciers that scientists study to understand past climates.

Tree Rings

The concentric rings on the cross-section of a tree trunk, representing a record of a tree's age and the conditions under which it grew.

Paleozoic

An era in the geologic time scale, approximately 541 to 252 million years ago, marked by the early development of life, including the Cambrian explosion.